The following morning, each participant was asked to sign a statement summarizing their activities over the course of the test—and falsely accusing them of hitting the escape key.

Half of those who had been up all night signed the document, compared to only 18% of those who had gotten a full night's sleep.

Lead researcher Kimberly Fenn said in a statement that “this is the first direct evidence that sleep deprivation increases the likelihood that a person will falsely confess to wrongdoing that never occurred." She added, “It’s a crucial first step toward understanding the role of sleep deprivation in false confessions and, in turn, raises complex questions about the use of sleep deprivation in the interrogation of innocent and guilty suspects.”

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The study should, indeed, be seen just as a first step. As Ars Technica points out, the stakes of the experiment may simply be too low for it to predict how sleepy innocents would behave when asked to sign a criminal confession. The participants don't face any tangible consequences for lying, and so it's hard to tell why exactly they behaved as they did. From Ars Technica:

People who rated their sleepiness as higher were more likely to sign the statement. That could mean that the more sleep-deprived someone feels, the more impaired their judgment is (as the researchers suggest). Or, it could mean that when someone is super-exhausted, their judgment about the long-term consequences of signing is fine; they just care a lot less about the personal embarrassment of some researcher thinking they deleted some experiment data.

But there's no doubt that false confessions are a real problem for our criminal justice system—according to The Innocence Project, roughly a quarter of people exonerated submitted false confessions. And there's also a lot of evidence that sleep deprivation can seriously impair your judgment, much in the way that alcohol does. Something we should all keep in mind.